Medication Summary
Use tetanus prophylaxis, analgesics, and antipruritics as needed. Reserve antibiotics for evidence of true infection and do not administer prophylactically. Carlton recommends antihistamines and observation alone as treatment for brown recluse spider bites. [18]
No commercial antivenom for loxoscelism is currently approved for use in the United States. A horse-derived FAB antivenom is available in Argentina, Peru, Brazil, and Mexico, and it is indicated for cutaneous loxoscelism and cutaneous hemolytic manifestations. [9, 19] It is only a matter of time before a suitable antivenom may be available in the United States.
Antibiotics
Class Summary
Antibiotics should not be used prophylactically. It has been suggested that antibiotics may minimize the local inflammatory component of cutaneous loxoscelism and decrease resulting skin necrosis.
Dapsone (Avlosulfon)
Dapsone is bactericidal and bacteriostatic against mycobacteria strains. The mechanism of action is similar to that of sulfonamides where competitive antagonists of p-aminobenzoic acids (PABA) prevent the formation of folic acid, causing bacterial growth inhibition.
If used, initiate the treatment with small doses followed by gradual increments. Monitor patients carefully because hypersensitivity, methemoglobinemia, and hemolysis in the presence of G-6-PD deficiency have been reported.
Corticosteroids
Class Summary
These agents have anti-inflammatory properties and cause profound and varied metabolic effects. In addition, these agents modify the body's immune response to diverse stimuli.
Use of corticosteroids is controversial in brown recluse spider bites. Evidence for using corticosteroids is insufficient.
Methylprednisolone (Solu-Medrol)
Methylprednisolone decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and reversing increased capillary permeability.
Prednisone (Deltasone, Orasone, Meticorten)
Prednisone decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and reversing increased capillary permeability.
Antihistamines
Class Summary
Antihistamines are used to treat minor allergic reactions and anaphylaxis. Diphenhydramine may be used to pretreat patients with prior documentation of minor allergic reactions. These agents may control itching by blocking effects of endogenously released histamine.
Diphenhydramine (Benadryl)
Diphenhydramine is used for symptomatic relief of allergic symptoms caused by histamine released in response to allergens.
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Classic finding of a vesicle with surrounding erythema at 24 hours following brown recluse envenomation. Photo by Thomas Arnold, MD.
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Illustration of a brown recluse spider with the fiddle displayed prominently on its dorsum.
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Spider envenomations, brown recluse. Envenomation site on inner thigh untreated at 1 week. Photo by Thomas Arnold, MD.
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Typical appearance of a male brown recluse spider. Photo contributed by Michael Cardwell, Victorville, Calif.
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Female brown recluse with size scale. Photo contributed by Michael Cardwell, Victorville, Calif.
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Spider envenomations, brown recluse. Close-up image of dorsal violin-shaped pattern. Photo contributed by Michael Cardwell, Victorville, Calif.
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Spider bite, brown recluse. Within an hour, the bite area swelled to the size of a quarter. The area turned blue and dark red by the evening of the first day, exceeding the boundaries of a circle drawn around the area of initial swelling by the patient's physician. Courtesy of Dale Losher.
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Spider bite, brown recluse. The third day after the bite. The skin continues to die. Courtesy of Dale Losher.
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Spider bite, brown recluse. Another view of the wound 3 days after the bite. Courtesy of Dale Losher.
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Spider bite, brown recluse. Nine days after the bite. The patient endured 8 days with an open wound to drain the spider's toxins and needed multiple doses of intravenous antibiotics and pain medication. Courtesy of Dale Losher.
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Spider bite, brown recluse. Eleven days after the bite. A 5-inch wide area of dead tissue was excised, necessitating skin grafting. Courtesy of Dale Losher.
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Spider bite, brown recluse. Waiting to see skin graft results 38 days after the bite. Courtesy of Dale Losher.
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Spider bite, brown recluse. Skin graft results 38 days after the bite. Courtesy of Dale Losher.
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Spider bite, brown recluse. View of healed wound approximately 10 months after bite. Courtesy of Dale Losher.
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Dermonecrotic arachnidism represents a local cutaneous injury with tissue loss and necrosis.
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Brown recluse spider. Courtesy of US Centers for Disease Control and Prevention.
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Brown recluse spider. Courtesy of US Centers for Disease Control and Prevention.
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Complete distribution range of wild and domestic Loxosceles reclusa (brown recluse spider). Courtesy of Wikimedia Commons (By ReliefUSA_map.gif: Public domain, U.S. government derivative work: Bob the Wikipedian).
